This invention relates to agricultural seed meters; and in particular, to an agricultural seed meter using a belt or drum to either singulate individual seeds for planting, as is commonly done in row crop planters, or to meter a plurality of smaller seeds of the type normally dispensed in grain drills, or the like.
U.S. Pat. No. 5,992,338 (Romans) discloses a meter of the type with which the present invention is concerned. In the belt meter disclosed in the ""338 patent, a single belt is entrained around two sprockets of equal size and having their axes of rotation located in a common horizontal plane, thus providing a horizontal upper run of the belt for seed selection and a horizontal lower return section. One of the sprockets is driven by a conventional drive arrangement which drives the sprocket at a rate proportional to ground speed. Seed is deposited into cells or pockets on the belt from a loading area above the upper run of the belt, excess seeds are removed from the pockets by a brush. Each seed is slated in a pocket as the belt travels around one of the sprockets and the pocket opens to facilitate release of the seed as it moves about the other sprocket.
The present invention provides a number of improvements over the prior meter described above. The prior belt meter, although capable of xe2x80x9csingulatingxe2x80x9d seed was not accurate enough to meter small seeds which are not singulated. Such smaller seeds are delivered in measured quantity (sometimes referred to as xe2x80x9cvolume meteringxe2x80x9d). As known in the art, larger seed, such as corn and soybeans, are separated or xe2x80x9csingulatedxe2x80x9d from a reservoir of seeds. The seeds are delivered in a steady stream, ideally spaced at constant intervals. The ability of a meter to deliver seeds at a constant spacing reliably and repeatedly at varying ground speeds is widely accepted as the primary function of seed meters for such row crops as corn and soybeans.
Crops such as wheat and milo having smaller seeds are commonly planted by metering the seed in volume. Because of the size of these smaller seeds and the higher density at which they are planted, it is difficult to meter such seed by volume accurately and reliably at desired ground speed. Obviously, if accuracy is not affected, all other things being equal, the farmer desires to plant at higher speeds to improve productivity. Smaller seeds are usually planted with a different meter than are the larger seeds mentioned or, if the same meter housing is used, the seed selection medium is changed according to the seed desired to be planted.
The present invention improves the accuracy of singulating larger seeds and it also provides a mechanism for allowing the same meter to plant smaller seeds without having to remove or change any parts in the meter. Rather, a simple rotation of a brush, called the xe2x80x9ccut-offxe2x80x9d brush, from the singulating position to a volume metering position provides the changeover. The meters do not have to be removed from the planter, and no parts need be substituted in, added to or removed from the meter for the changeover.
Further, the belt embodiment of the present invention provides two seed delivery belts, arranged in side-by-side relation, to select and deliver the seeds. This enables the meter to be designed in a more compact arrangement for the same delivery capacity and ground speed.
The delivery belts are entrained about three sprockets, rather than two as in the prior art. This arrangement, with the axes of the sprockets arranged in a triangle, provides an upper, generally horizontal loading section or leg, a generally vertical delivery section, and an inclined return section. Seeds are received from the conventional seed hopper of the planter and moved under gravity into a buffer zone or area above the loading section of the belt, which is inclined slightly upwardly relative to the horizontal and in the direction of belt movement. A cut-off or singulating brush, when arranged in the singulating position, is located above the end of the loading section of the brush and inclined at an oblique angle relative to the loading section of the brush. The cut-off brush is positioned close to the belt to remove seeds not seated in the pockets of the belt and, because of the friction between the belt to remove unseated seeds. The oblique inclination of the cut-off brush, lifts the removed seeds for recirculation in the buffer zone.
The seated seeds are then conveyed downwardly to a lower sprocket where the belt moves around the lower sprocket; and the pockets are urged open to facilitate release of the seeds into a generally upright delivery tube. A retainer brush having bristles extending parallel to the direction of seed travel along the delivery leg retains the seated seeds in the pockets until they reach the end of the retainer brush at which point the belt travels around the lower sprocket. This arrangement provides for an improved accuracy in the release of the seeds which, in turn, permits the seeds to be released reliably and repeatedly over the inlet opening of the discharge tube. This, in turn, reduces seed xe2x80x9cbouncexe2x80x9d as the seeds drop through the discharge tube and into the formed furrow. The accuracy and repeatability of seed spacing in the furrow, for singulated seeds, is thus enhanced.
When the cut-off brush is moved to the volume metering position, it provides an opening for metering seeds which are seated in the seed pockets in fixed volume. The cut-off brush, in the volume metering position, defines an acute angle with the adjacent region of the belt to narrow the opening. This provides a conformance with the retainer brush which continues to retain the measured quantity of smaller seeds in the seed pockets until the belt reaches the release point, thereby providing an accurately measured and accurately released stream of seed delivered in volume or bulk form.
Other features and advantages of the invention will be appreciated as they are disclosed in the specification, accompanied by the attached drawing, wherein like reference numerals refer to like parts in the various views.